Phosphor screen and displays systems

• US 7,733,571 B1
• Filed: 07/24/2007
• Issued: 06/08/2010
• Est. Priority Date: 07/24/2007
• Status: Expired due to Fees

• Current Assignee: Rockwell Collins, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Rockwell Collins, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Li, Shu
• Primary Examiner(s): Schwartz; Jordan M.
• Assistant Examiner(s): JONES, JAMES
• Application Number:
  US11/880,850
• Time in Patent Office: 1,050 Days
• Field of Search: 359/630, 359/262
• US Class Current: 359/630
• CPC Class Codes: G02B 2027/0118 comprising devices for improving the contrast of the display / brillance control visibility
• CPC Class Codes: G02B 27/01 Head-up displays
• CPC Class Codes: G02B 5/20 Filters polarising elements G02B5/30

Abstract

A phosphor screen for image forming including phosphor material being excitable by light in a wavelength λ1. The phosphor screen receives an optical image from an image forming optical system and produces the optical image at a second wavelength λ2. The phosphor screen includes a phosphor layer comprising the phosphor material. A short-pass reflective coating is positioned on a first side of the phosphor layer. The short-pass reflective coating transmits the wavelength λ1 and reflects the wavelength λ2. A long-pass reflective coating is positioned on a second side of the phosphor layer. The long-pass reflective coating transmits the wavelength λ2 and reflects the wavelength λ1. A first substrate is positioned over the short-pass reflective coating. The first substrate is formed of optically clear and thermal conductive material. A second substrate is positioned over the long-pass reflective coating. The second substrate is formed of long-pass absorptive optical filter material that transmits the wavelength λ2 and absorbs wavelength λ1 from ambient light to prevent the phosphor layer from being excited by the ambient light. The phosphor screen may alternatively be used for a direct-view visual display apparatus. These principles can also be utilized for backlighting and general illumination applications.

Claims

1. A visual display apparatus, comprising:

a) an excitation light source for providing light in a first wavelength λ

1;

b) a light modulating device for receiving light from said excitation light source and modulating said light to form an image;

c) an imaging forming optical system for receiving outputted light from said light modulating device and magnifying and relaying said image; and

,

d) a phosphor screen, comprising phosphor material being excitable by light in said first wavelength λ

1, said phosphor screen for receiving said optical image from said image forming optical system and producing said optical image at a second wavelength λ

2, said phosphor screen, comprising;

i. a phosphor layer comprising said phosphor material emitting said second wavelength λ

2;

ii. a short-pass reflective coating positioned on a first side of said phosphor layer, said short-pass reflective coating for transmitting said wavelength λ

1 and reflecting said wavelength λ

2;

iii. a long-pass reflective coating positioned on a second side of said phosphor layer, said long-pass reflective coating for transmitting said wavelength λ

2 and reflecting said wavelength λ

1;

iv. a first substrate positioned over said short-pass reflective coating, said first substrate being formed of optically clear and thermal conductive material for transmitting said wavelength λ

1 and dissipating heat generated by said phosphor layer during high intensity operation; and

,

v. a second substrate positioned over said long-pass reflective coating, said second substrate being formed of long-pass absorptive optical filter material that transmits said second wavelength λ

2 and absorbs said wavelength λ

1 from the ambient light for improving display contrast ratio in bright ambient conditions,

wherein said first substrate comprises optically clear and thermal conductive material having a thermal conductivity in a range of 0.7 watt/(K·

m) to 30 watt/(K·

m).

2. The visual display apparatus of claim 1, wherein said phosphor layer comprises phosphor particles with an average granular size in a range from 1.0 nm to 10 μ

m, deposited at a thickness in a range from 0.01 mm to 0.50 mm.

3. The visual display apparatus of claim 1, wherein said phosphor layer comprises phosphor particles with an average granular size in a range from 1.5 nm to 5.0 μ

m, deposited at a thickness in a range from 0.05 mm to 0.25 mm.

4. The visual display apparatus of claim 1, wherein said phosphor material is a chemical composition of alkaline earth or rare-earth metal salts of aluminate, silicate, oxynitride, nitride, chalcogenides of cadmium or zinc, or combinations of the same, that are excitable by light at said first wavelength λ

1 in a range of from 360 nm to 480 nm.

6. The visual display apparatus of claim 1, wherein said phosphor layer comprises a single phosphor for emission of a single color at dominant wavelength λ

2, or a mixture of multiple phosphors for emission of multi-color spectrum or white light.

7. The visual display apparatus of claim 1, wherein said phosphor material comprises a chemical composition that emits light at said second wavelength λ

2 in the visible wavelength range, from 400 nm to 650 nm.

8. The visual display apparatus of claim 1, wherein said first substrate comprises optically clear and thermal conductive material having a thermal conductivity in a range of 1.0 watt/(K·

m) to 20 watt/(K·

m).

9. The visual display apparatus of claim 1, wherein said light modulating device comprises:

a transmissive liquid crystal display, a reflective liquid crystal display, a micro-mirror array, or a spatial light modulator.

10. The visual display apparatus of claim 1, wherein said excitation light source comprises a solid state device consisting of:

a) at least one light emitting diode (LED) for emitting light of said first wavelength in a range of from 360 nm to 480 nm;

b) an optical element that collects and directs the light from an LED device wavelength toward said phosphor layer; and

,

c) an optical element that distributes the light emission from an LED device uniformly over the phosphor layer.

11. A visual display apparatus of claim 1, wherein said excitation light source comprises a solid state device selected from the group consisting of:

a) single or multiple laser sources in a form of an array, emitting light of said first wavelength from 360 nm to 480 nm;

b) an optical element that collimates and combines multiple laser beams and directs the light at said second wavelength; and

,

c) an optical element that distributes the light emission from a laser source uniformly over the phosphor layer.

5. A visual display apparatus, comprising:

a) an excitation light source for providing light in a first wavelength λ

1;

b) a light modulating device for receiving light from said excitation light source and modulating said light to form an image;

c) an imaging forming optical system for receiving outputted light from said light modulating device and magnifying and relaying said image; and

,

d) a phosphor screen, comprising phosphor material being excitable by light in said first wavelength λ

1, said phosphor screen for receiving said optical image from said image forming optical system and producing said optical image at a second wavelength λ

2, said phosphor screen, comprising;

i. a phosphor layer comprising said phosphor material emitting said second wavelength λ

2;

ii. a short-pass reflective coating positioned on a first side of said phosphor layer, said short-pass reflective coating for transmitting said wavelength λ

1 and reflecting said wavelength λ

2;

iii. a long-pass reflective coating positioned on a second side of said phosphor layer, said long-pass reflective coating for transmitting said wavelength λ

2 and reflecting said wavelength λ

1;

iv. a first substrate positioned over said short-pass reflective coating, said first substrate being formed of optically clear and thermal conductive material for transmitting said wavelength λ

1 and dissipating heat generated by said phosphor layer during high intensity operation; and

,

v. a second substrate positioned over said long-pass reflective coating, said second substrate being formed of long-pass absorptive optical filter material that transmits said second wavelength λ

2 and absorbs said wavelength λ

1 from the ambient light for improving display contrast ratio in bright ambient conditions,

wherein said phosphor material comprises a chemical composition of cadmium chalcogenide and zinc chalcogenide, with said cadmium chalcogenide forming the core of the phosphor particle and zinc chalcogenide forming a shell covering the cadmium chalcogenide core, said core-shell phosphor particle having a particle size in the range of 1.0 nm to 3.0 nm, that emits light at said second wavelength λ

2 in the visible wavelength range, from 500 nm to 600 nm, when excited by said first wavelength λ

1 at a wavelength range of from 360 nm to 480 nm.

12. A phosphor screen for image forming, comprising phosphor material being excitable by light in a wavelength λ

1, said phosphor screen for receiving an optical image from an image forming optical system and producing said optical image at a wavelength λ

2, said phosphor screen, comprising;

a) a phosphor layer comprising said phosphor material;

b) a short-pass reflective coating positioned on a first side of said phosphor layer, said short-pass reflective coating for transmitting said wavelength λ

1 and reflecting said wavelength λ

2;

c) a long-pass reflective coating positioned on a second side of said phosphor layer, said long-pass reflective coating for transmitting said wavelength λ

2 and reflecting said wavelength λ

1;

d) a first substrate positioned over said short-pass reflective coating, said first substrate being formed of optically clear and thermal conductive material; and

,

e) a second substrate positioned over said long-pass reflective coating, said second substrate being formed of long-pass absorptive optical filter material that transmits said wavelength λ

2 and absorbs wavelength λ

1 from ambient light to prevent said phosphor layer from being excited by the ambient light,

wherein said first substrate comprises optically clear and thermal conductive material having a thermal conductivity in a range of 0.7 watt/(K·

m) to 30 watt/(K·

m).

13. A Heads-Up-Display (HUD) system, comprising:

a) visual display apparatus, comprising;

i. an excitation light source for providing light in a first wavelength λ

1;

ii. a light modulating device for receiving light from said excitation light source and modulating said light to form an image;

iii. an imaging forming optical system for receiving outputted light from said light modulating device and magnifying and relaying said image; and

,

iv. a phosphor screen, comprising phosphor material being excitable by light in said first wavelength λ

1, said phosphor screen for receiving said optical image from said image forming optical system and producing said optical image at a second wavelength (λ

2), said phosphor screen, comprising;

1. a phosphor layer comprising said phosphor material emitting said second wavelength λ

2;

2. a short-pass reflective coating positioned on a first side of said phosphor layer, said short-pass reflective coating for transmitting said wavelength λ

1 and reflecting said wavelength λ

2;

3. a long-pass reflective coating positioned on a second side of said phosphor layer, said long-pass reflective coating for transmitting said wavelength λ

2 and reflecting said wavelength λ

1;

4. a first substrate positioned over said short-pass reflective coating, said first substrate being formed of optically clear and thermal conductive material for transmitting said wavelength λ

1 and dissipating heat generated by said phosphor layer during high intensity operation; and

,

5. a second substrate positioned over said long-pass reflective coating, said second substrate being formed of long-pass absorptive optical filter material that transmits said second wavelength λ

2 and absorbs wavelength λ

1 said wavelength λ

1 from the ambient light for improving display contrast ratio in bright ambient conditions;

b) a relay optics system for receiving said optical image at said second wavelength λ

2 from said visual display apparatus and forming a relayed image at an observer'"'"'s eye;

c) a mirror positioned to receive said relayed image from said relay optics system and changing the direction of light thereof; and

,

d) a see-through imaging combiner that combines real scenery and said relayed image from said relay optics.

14. A phosphor screen for image forming, comprising phosphor material being excitable by light in a wavelength λ

1, said phosphor screen for receiving an optical image from an image forming optical system and producing said optical image at a wavelength λ

2, said phosphor screen, comprising;

a) a phosphor layer comprising said phosphor material;

b) a short-pass reflective coating positioned on a first side of said phosphor layer, said short-pass reflective coating for transmitting said wavelength λ

1 and reflecting said wavelength λ

2;

c) a long-pass reflective coating positioned on a second side of said phosphor layer, said long-pass reflective coating for transmitting said wavelength λ

2 and reflecting said wavelength λ

1;

d) a first substrate positioned over said short-pass reflective coating, said first substrate being formed of optically clear and thermal conductive material; and

,

e) a second substrate positioned over said long-pass reflective coating, said second substrate being formed of long-pass absorptive optical filter material that transmits said wavelength λ

2 and absorbs wavelength λ

1 from ambient light to prevent said phosphor layer from being excited by the ambient light,

wherein said phosphor material comprises a chemical composition of cadmium chalcogenide and zinc chalcogenide, with said cadmium chalcogenide forming the core of the phosphor particle and zinc chalcogenide forming a shell covering the cadmium chalcogenide core, said core-shell phosphor particle having a particle size in the range of 1.0 nm to 3.0 nm, that emits light at said second wavelength λ

2 in the visible wavelength range, from 500 nm to 600 nm, when excited by said first wavelength λ

1 at a wavelength range of from 360 nm to 480 nm.